Low-Sodium Diets Could Prevent Kidney Failure, Heart Disease

Lowering the salt intake of heart and kidney patients could help prevent renal failure or cardiovascular disease, according to new research appearing online in Thursday’s edition of the Journal of the American Society of Nephrology.

Excessive sodium consumption is frequently associated with an increased risk of heart disease and declining kidney function, and chronic kidney disease (CKD) patients are more likely to be affected due to the vital role the organ plays in maintaining salt balance. However, the impact of salt restriction on these individuals had not previously been analyzed in great depth, the study authors explained in a statement.

Principal investigator Dr. Katrina Campbell, a research fellow at Australia’s Princess Alexandra Hospital, and her colleagues conducted what they are calling the first blinded, randomized, controlled trial comparing high sodium (180 to 200 mmol/day) and low sodium (60 to 80 mmol/day) diets in CKD patients – the LowSALT CKD study.

Dr. Campbell, University of Queensland PhD candidate Emma McMahon and their associates maintained each diet for two weeks each in a random order in 20 kidney disease patients. Most health officials recommend consuming no more than 100 mmol (2300 mg or one teaspoon) of salt each day.

They measured extracellular fluid volume, blood pressure, protein levels in the urine, and other parameters associated with heart and kidney health. On average, they found that low sodium consumption reduced excess extracellular fluid volume by one liter, lowered blood pressure by 10/4 mm Hg, and halved protein excretion in the urine. Furthermore, they reported no significant side effects during the course of the study.

“These are clinically significant findings, with this magnitude of blood pressure reduction being comparable to that expected with the addition of an anti-hypertensive medication and larger than effects usually seen with sodium restriction in people without CKD,” McMahon said.

She added the 50 percent reduction in protein excretion in the urine was particularly of note, and that if it could be maintained long-term, it could result in a 30 percent decrease in the risk of the condition progressing to end-stage kidney disease requiring dialysis or transplant.

All told, the authors believe that their findings suggest that restricting sodium intake could be a safe, effective and inexpensive way to reduce cardiovascular risk and prevent the kidney function of CKD patients from worsening.

“If these findings are transferable to the larger CKD population and shown to be sustainable long-term, this could translate to markedly reduced risk of cardiovascular events and progression to end-stage kidney disease, and it could generate considerable health-care savings,” Dr. Campbell noted.